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Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073)

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Mon, 13 Oct 2008 12:29:20 +0200
To: www-svg@w3.org
Message-Id: <200810131229.20615.Dr.O.Hoffmann@gmx.de>

Anthony Grasso:

>
> Please let me know if you still have problems viewing it.
>

Hello,

this works, maybe because Opera has no problems with
it, it may occur not only with animation or zooming 
(I think, typically zooming can be excluded, because this
is only a scaling with a positive factor and for this an 
inverse always exists), my suggestion would be to write 
something like this (This way I think, it is easier to provide
a simple method for authors, how to analyse the problem):

"Note that the inverse of the CTM may not always exist. 
This may cause problems for a user-agent, if the constrained 
transformation is realised using the inverse of the CTM.
Authors are encouraged to verify that the resultant CTM is always 
invertable to avoid unexpected results. Mathematically it is invertable,
if the determinant of the CTM is defined and not zero, graphically
this is the case, if a two-dimensional shape remains two-dimensionally
before the effect of a constrained transformation is applied."


Olaf
Received on Monday, 13 October 2008 10:37:46 GMT

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